how to use apply on whole df code example

Example 1: pandas apply function to column

df['a'] = df['a'].apply(lambda x: x + 1)

Example 2: pandas apply function to each row lambda

def EOQ(D,p,ck,ch):
    Q = math.sqrt((2*D*ck)/(ch*p))
    return Q
ch=0.2
ck=5
df['Q'] = df.apply(lambda row: EOQ(row['D'], row['p'], ck, ch), axis=1)
df